Due to the worldwide growth in population and industrialization, along with natural disasters, world supplies of safe drinking water are dwindling. Key pollutants that pose a threat to humans via polluted water consumption are, pathogens (bacteria and viruses), organics, halogenated organics and heavy metals. Conventional water filters are commonly used in American households to remove water impurities and to provide cleaner, more aesthetically pleasing drinking water. However, there are numerous limitations that make these systems difficult to use. They are expensive, bulky, difficult to install and replace, can harbor growth of harmful organisms, are inconvenient, and none claim to remove or kill 100 percent of all pathogens, although most are effective in removing some organics (including halogenated organics) as well as some heavy metals.
Small disposable filters such as those sold under the trade designation Brita.RTM., are expensive by world standards. They can also be somewhat cumbersome to use. A distinct drawback to these types of filtration devices is that they are designed for use in water which is microbiologically safe. That is, the devices are not designed to remove pathogens because it is assumed that the water is pathogen free. Additionally, these devices have only limited utility in the removal of harmful substances such as, for example, heavy metals.
It is difficult for many people in the world, including world travelers, to obtain safe drinking water without having to endure the inconvenience of disinfecting it by either boiling it or through the use of iodine-based disinfectants. In many locales, iodine-based disinfectants are not readily available. When available, it is well known that some of the iodine-based disinfectant systems currently being deployed leave a distinctively bad taste in the mouth. Additionally, due to the fact that the iodine is consumed, potentially adverse medical effects can arise, especially for individuals having thyroid problems. In any event, these methods do nothing to remove metals and organics.
Some of the presently available iodine-based products for the disinfection of water for drinking purposes have overcome the potential medical difficulties which may present themselves due to the consumption of iodine. One such product is manufactured by AccuFilter International, Inc. under the trade designation "THE STRAW". This device is an opaque tubular object which is inserted into the water to be disinfected. At the base of the tube, on the inside, is a disinfecting medium of iodine. Further up the tube, on the inside, is a matrix of activated carbon. In use, the base of the tube is inserted into the water to be disinfected and the consumer sucks on the other end thereby pulling the water through the iodine medium and, thereafter, through the matrix of activated carbon. As the water passes through the iodine medium, it is disinfected. Thereafter, as the iodine-loaded water is passed through the matrix of activated carbon, substantially all of the iodine is removed. The manufacturer states that water sucked out of "The Straw" will be disinfected and substantially free of iodine. A warning to those individuals having thyroid problems is present. They are instructed to consult their doctor prior to using the device.
Another presently available device is manufactured by Recovery Engineering Inc. under the trade designation "The Pur Explorer". This device is a canister having a plunger arrangement which can force water through an iodine-based disinfectant to achieve potability of the water. A product review in the August, 1994 issue of "Outside" magazine states that the Pur Explorer is certified by the EPA to deactivate all types of waterborne infectious agents, including viruses. This is achieved by passing the water through an iodine matrix during the filtration process. It is also stated that an optional carbon cartridge removes the small amount of iodine from the filtered water.
Yet another presently available commercial system is marketed under the trade designation POTABLE AQUA.RTM. WITH P.A. PLUS by Wisconsin Pharmacal Co., Inc. of Jackson Wis. Two separate tablets which are separately and sequentially added to water to be purified are involved in this system. First, a POTABLE AQUA.RTM. tablet is added to one quart of water to be purified. (Two tablets are to be used if contamination of the water with Giardia is suspected.) The active ingredient of the tablet is tetraglycine hydroperiodide (16.7%). That is, each tablet contains 6.68% of titratable iodine. The POTABLE AQUA.RTM. tablet is allowed to dissolve in the water for ten (10) minutes. (Twenty minutes are recommended if Giardia is suspected.) At this point, the water is faintly colored orange. Thereafter, one P.A. PLUS tablet is added to the quart of water in order to neutralize the iodine taste instilled in the water by the POTABLE AQUA.RTM. tablet. The active ingredient in the P.A. PLUS tablet is ascorbic acid. Each P.A. PLUS tablet contains 45 milligrams (mg) of ascorbic acid. After addition of the P.A. PLUS tablet the container is shaken and three (3) minutes are allowed to pass. Thereafter, the water turns clear in color and is drinkable. Importantly, the literature accompanying the system states that the POTABLE AQUA.RTM. tablet and the P.A. PLUS tablet must not be added to the water at the same time. Also stated is that adding the P.A. PLUS tablet before the expiration of the twenty minute period may allow harmful organisms to remain in the water. Clearly, this system involves the sequential addition of the two tablets.
While all of these devices do address the problems associated with the bad taste of iodine-based disinfectants and the concomitant medical problems which may be associated with the ingestion of large amounts of iodine, none of these products offer the consumer a single step product which gives a reliable visual indication after the disinfection process has been completed and the water is safe to drink. In particular, while the POTABLE AQUA.RTM. WITH P.A. PLUS does provide a visual indication, the indication is not that the water has been purified, but rather that the iodine present due to the predetermined, timed, first step has been removed. In other words, a consumer utilizing either of these products must take it on faith that the product has performed satisfactorily and the water is, in fact, safe to drink. Importantly, with the POTABLE AQUA.RTM. WITH P.A. PLUS system, the consumer without independent timing mechanisms such as a watch is at a distinct disadvantage in determining the point in time that the water is safe to drink.
From the above, it is clear that there exists a distinct need for a one-step process and article which allows a consumer to disinfect or otherwise purify water without having to resort to an independent timing mechanism. That is, there is a distinct need for a process and article which provides a visual indication after the purification process is complete and the water is safe to drink.